Hemodialysis removes toxic substances and metabolic waste from the bloodstream using an extracorporeal circuit with components designed to perform ultrafiltration and diffusion on the blood. Before the blood is returned to the body, air bubbles are removed from the blood to inhibit embolisms. The process of removing air is typically accomplished through use of a venous drip chamber, which is located downstream of the blood outlet of a dialyzer and directly upstream of the venous blood return of the patient. A level detector is used to ensure that an associated clamp closes when the venous drip chamber blood level drops below a certain level to prevent air from entering into the patient.
Devices are known that provide for air removal through use of a micro-porous membrane and a vent structure associated with the venous drip chamber. Such devices generally involve use of a specialized module for attachment to a specialized blood tubing cassette. Reference is made, for example, to U.S. Pat. Nos. 8,187,466 B2 and 7,938,967 B2, both to Folden et al. and entitled “Safety vent Structure for extracorporeal circuit” and U.S. Pat. No. 8,038,886 B2 to Folden et al., entitled “Medical hemodialysis container including a self sealing vent,” which are all incorporated herein by reference and which disclose air-release devices that include a porous material capable of swelling when moistened such that the vent structure can inhibit liquid from escaping the air-release device during use. For discussion of other air-release devices used in extracorporeal fluid circuits, reference is also made to U.S. Pat. No. 8,506,684 B2 to Weaver et al., entitled “Gas release devices for extracorporeal fluid circuits and related methods” and U.S. Pat. No. 8,663,463 to Weaver et al., entitled “Extracorporeal fluid circuit and related components,” which are incorporated herein by reference.
Accordingly, it would be desirable to provide a deaeration device for an extracorporeal circuit that may be advantageously integrated into and operate with existing hemodialysis machines and/or associated devices, including devices performing measurements on blood in the extracorporeal circuit.